/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.sun.org.apache.xml.internal.security.algorithms.implementations;

import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Signature;
import java.security.SignatureException;
import java.security.spec.AlgorithmParameterSpec;

import com.sun.org.apache.xml.internal.security.algorithms.JCEMapper;
import com.sun.org.apache.xml.internal.security.algorithms.SignatureAlgorithmSpi;
import com.sun.org.apache.xml.internal.security.signature.XMLSignatureException;
import com.sun.org.apache.xml.internal.security.utils.Base64;
import com.sun.org.apache.xml.internal.security.utils.Constants;

public class SignatureDSA extends SignatureAlgorithmSpi {

  /**
   * {@link org.apache.commons.logging} logging facility
   */
  private static java.util.logging.Logger log =
      java.util.logging.Logger.getLogger(SignatureDSA.class.getName());

  /**
   * Field URI
   */
  public static final String URI = Constants.SignatureSpecNS + "dsa-sha1";

  /**
   * Field algorithm
   */
  private java.security.Signature signatureAlgorithm = null;

  /**
   * Method engineGetURI
   *
   * @inheritDoc
   */
  protected String engineGetURI() {
    return SignatureDSA.URI;
  }

  /**
   * Constructor SignatureDSA
   */
  public SignatureDSA() throws XMLSignatureException {
    String algorithmID = JCEMapper.translateURItoJCEID(SignatureDSA.URI);
    if (log.isLoggable(java.util.logging.Level.FINE)) {
      log.log(java.util.logging.Level.FINE, "Created SignatureDSA using " + algorithmID);
    }

    String provider = JCEMapper.getProviderId();
    try {
      if (provider == null) {
        this.signatureAlgorithm = Signature.getInstance(algorithmID);
      } else {
        this.signatureAlgorithm =
            Signature.getInstance(algorithmID, provider);
      }
    } catch (java.security.NoSuchAlgorithmException ex) {
      Object[] exArgs = {algorithmID, ex.getLocalizedMessage()};
      throw new XMLSignatureException("algorithms.NoSuchAlgorithm", exArgs);
    } catch (java.security.NoSuchProviderException ex) {
      Object[] exArgs = {algorithmID, ex.getLocalizedMessage()};
      throw new XMLSignatureException("algorithms.NoSuchAlgorithm", exArgs);
    }
  }

  /**
   * @inheritDoc
   */
  protected void engineSetParameter(AlgorithmParameterSpec params)
      throws XMLSignatureException {
    try {
      this.signatureAlgorithm.setParameter(params);
    } catch (InvalidAlgorithmParameterException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected boolean engineVerify(byte[] signature)
      throws XMLSignatureException {
    try {
      if (log.isLoggable(java.util.logging.Level.FINE)) {
        log.log(java.util.logging.Level.FINE, "Called DSA.verify() on " + Base64.encode(signature));
      }

      byte[] jcebytes = SignatureDSA.convertXMLDSIGtoASN1(signature);

      return this.signatureAlgorithm.verify(jcebytes);
    } catch (SignatureException ex) {
      throw new XMLSignatureException("empty", ex);
    } catch (IOException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected void engineInitVerify(Key publicKey) throws XMLSignatureException {
    if (!(publicKey instanceof PublicKey)) {
      String supplied = publicKey.getClass().getName();
      String needed = PublicKey.class.getName();
      Object exArgs[] = {supplied, needed};

      throw new XMLSignatureException("algorithms.WrongKeyForThisOperation", exArgs);
    }

    try {
      this.signatureAlgorithm.initVerify((PublicKey) publicKey);
    } catch (InvalidKeyException ex) {
      // reinstantiate Signature object to work around bug in JDK
      // see: http://bugs.sun.com/view_bug.do?bug_id=4953555
      Signature sig = this.signatureAlgorithm;
      try {
        this.signatureAlgorithm = Signature.getInstance(signatureAlgorithm.getAlgorithm());
      } catch (Exception e) {
        // this shouldn't occur, but if it does, restore previous
        // Signature
        if (log.isLoggable(java.util.logging.Level.FINE)) {
          log.log(java.util.logging.Level.FINE, "Exception when reinstantiating Signature:" + e);
        }
        this.signatureAlgorithm = sig;
      }
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected byte[] engineSign() throws XMLSignatureException {
    try {
      byte jcebytes[] = this.signatureAlgorithm.sign();

      return SignatureDSA.convertASN1toXMLDSIG(jcebytes);
    } catch (IOException ex) {
      throw new XMLSignatureException("empty", ex);
    } catch (SignatureException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected void engineInitSign(Key privateKey, SecureRandom secureRandom)
      throws XMLSignatureException {
    if (!(privateKey instanceof PrivateKey)) {
      String supplied = privateKey.getClass().getName();
      String needed = PrivateKey.class.getName();
      Object exArgs[] = {supplied, needed};

      throw new XMLSignatureException("algorithms.WrongKeyForThisOperation", exArgs);
    }

    try {
      this.signatureAlgorithm.initSign((PrivateKey) privateKey, secureRandom);
    } catch (InvalidKeyException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected void engineInitSign(Key privateKey) throws XMLSignatureException {
    if (!(privateKey instanceof PrivateKey)) {
      String supplied = privateKey.getClass().getName();
      String needed = PrivateKey.class.getName();
      Object exArgs[] = {supplied, needed};

      throw new XMLSignatureException("algorithms.WrongKeyForThisOperation", exArgs);
    }

    try {
      this.signatureAlgorithm.initSign((PrivateKey) privateKey);
    } catch (InvalidKeyException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected void engineUpdate(byte[] input) throws XMLSignatureException {
    try {
      this.signatureAlgorithm.update(input);
    } catch (SignatureException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected void engineUpdate(byte input) throws XMLSignatureException {
    try {
      this.signatureAlgorithm.update(input);
    } catch (SignatureException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * @inheritDoc
   */
  protected void engineUpdate(byte buf[], int offset, int len) throws XMLSignatureException {
    try {
      this.signatureAlgorithm.update(buf, offset, len);
    } catch (SignatureException ex) {
      throw new XMLSignatureException("empty", ex);
    }
  }

  /**
   * Method engineGetJCEAlgorithmString
   *
   * @inheritDoc
   */
  protected String engineGetJCEAlgorithmString() {
    return this.signatureAlgorithm.getAlgorithm();
  }

  /**
   * Method engineGetJCEProviderName
   *
   * @inheritDoc
   */
  protected String engineGetJCEProviderName() {
    return this.signatureAlgorithm.getProvider().getName();
  }

  /**
   * Converts an ASN.1 DSA value to a XML Signature DSA Value.
   *
   * The JAVA JCE DSA Signature algorithm creates ASN.1 encoded (r,s) value
   * pairs; the XML Signature requires the core BigInteger values.
   *
   * @return the decode bytes
   * @see <A HREF="http://www.w3.org/TR/xmldsig-core/#dsa-sha1">6.4.1 DSA</A>
   */
  private static byte[] convertASN1toXMLDSIG(byte asn1Bytes[]) throws IOException {

    byte rLength = asn1Bytes[3];
    int i;

    for (i = rLength; (i > 0) && (asn1Bytes[(4 + rLength) - i] == 0); i--) {
      ;
    }

    byte sLength = asn1Bytes[5 + rLength];
    int j;

    for (j = sLength;
        (j > 0) && (asn1Bytes[(6 + rLength + sLength) - j] == 0); j--) {
      ;
    }

    if ((asn1Bytes[0] != 48) || (asn1Bytes[1] != asn1Bytes.length - 2)
        || (asn1Bytes[2] != 2) || (i > 20)
        || (asn1Bytes[4 + rLength] != 2) || (j > 20)) {
      throw new IOException("Invalid ASN.1 format of DSA signature");
    }
    byte xmldsigBytes[] = new byte[40];

    System.arraycopy(asn1Bytes, (4 + rLength) - i, xmldsigBytes, 20 - i, i);
    System.arraycopy(asn1Bytes, (6 + rLength + sLength) - j, xmldsigBytes,
        40 - j, j);

    return xmldsigBytes;
  }

  /**
   * Converts a XML Signature DSA Value to an ASN.1 DSA value.
   *
   * The JAVA JCE DSA Signature algorithm creates ASN.1 encoded (r,s) value
   * pairs; the XML Signature requires the core BigInteger values.
   *
   * @return the encoded ASN.1 bytes
   * @see <A HREF="http://www.w3.org/TR/xmldsig-core/#dsa-sha1">6.4.1 DSA</A>
   */
  private static byte[] convertXMLDSIGtoASN1(byte xmldsigBytes[]) throws IOException {

    if (xmldsigBytes.length != 40) {
      throw new IOException("Invalid XMLDSIG format of DSA signature");
    }

    int i;

    for (i = 20; (i > 0) && (xmldsigBytes[20 - i] == 0); i--) {
      ;
    }

    int j = i;

    if (xmldsigBytes[20 - i] < 0) {
      j += 1;
    }

    int k;

    for (k = 20; (k > 0) && (xmldsigBytes[40 - k] == 0); k--) {
      ;
    }

    int l = k;

    if (xmldsigBytes[40 - k] < 0) {
      l += 1;
    }

    byte asn1Bytes[] = new byte[6 + j + l];

    asn1Bytes[0] = 48;
    asn1Bytes[1] = (byte) (4 + j + l);
    asn1Bytes[2] = 2;
    asn1Bytes[3] = (byte) j;

    System.arraycopy(xmldsigBytes, 20 - i, asn1Bytes, (4 + j) - i, i);

    asn1Bytes[4 + j] = 2;
    asn1Bytes[5 + j] = (byte) l;

    System.arraycopy(xmldsigBytes, 40 - k, asn1Bytes, (6 + j + l) - k, k);

    return asn1Bytes;
  }

  /**
   * Method engineSetHMACOutputLength
   */
  protected void engineSetHMACOutputLength(int HMACOutputLength) throws XMLSignatureException {
    throw new XMLSignatureException("algorithms.HMACOutputLengthOnlyForHMAC");
  }

  /**
   * Method engineInitSign
   */
  protected void engineInitSign(
      Key signingKey, AlgorithmParameterSpec algorithmParameterSpec
  ) throws XMLSignatureException {
    throw new XMLSignatureException("algorithms.CannotUseAlgorithmParameterSpecOnDSA");
  }
}
